The present disclosure relates to image forming apparatuses, such as electrographic copiers, printers, facsimile machines, multifunction peripherals including two or more of them, etc. and methods for reducing image deletion.
Recently, amorphous silicon (a-Si) photosensitive drums are widely used as image bearing members for image forming apparatuses that employ an electrographic process. An a-Si photosensitive drum is high in hardness and has excellent durability. Accordingly, the characteristics as a photoreceptor may hardly degrade even after long term use and can maintain high image quality. In other words, its running cost may be low, and handling may be easy. Further, it can exhibit greater safety in environment. The a-Si photosensitive drum is an excellent image bearing member.
It has been known that image deletion is liable to be caused in an image forming apparatus with the a-Si photosensitive drum because of its characteristics. The image deletion means a phenomenon that toner runs around an image. The image deletion occurs in a way that an ion generating substance adhering to the photosensitive drum takes moisture in the air. Specifically, when the surface of the photosensitive drum is electrically charged with the use of a charger, nitrogen oxide (NOx) adheres to the surface of the photosensitive drum to take the moisture in the air. As a result, image deletion may be caused around the edge of an electrostatic latent image formed on the surface of the photosensitive drum.
Various methods for reducing occurrence of image deletion have been proposed. For example, a heating element (heater) is provided in the interior of the photosensitive drum. The heater generates heat on the basis of the temperature and humidity detected by a temperature/humidity sensor in the apparatus. This can evaporate the moisture adhering to the surface of the photosensitive drum, thereby reducing occurrence of image deletion.
Alternatively, some image forming apparatus includes a static eliminating section. The static eliminating section causes a light emitting element mounted on one of the surfaces of a substrate to emit light to irradiate the light to the photosensitive drum, thereby eliminating static electricity on the photosensitive drum. A heating element to heat the photosensitive drum is provided on the other surface of the substrate. Thus, occurrence of image deletion can be reduced.